The Falcon 9 lifted off from Launch Complex 39A at NASA’s Kennedy Space Center in Florida at 12:31 p.m. Eastern, and deployed the Dragon spacecraft into low Earth orbit 10 minutes later. Neither NASA nor SpaceX reported any issues during the countdown or liftoff. The Dragon, flying a mission designated SpX-12, will arrive at the ISS early Aug. 16.

The Falcon 9’s first stage also made a successful landing at Landing Zone 1, a former launch site at Cape Canaveral Air Force Station now used by SpaceX for landing first stages.

The landing was the 14th successful landing in 39 Falcon 9 liftoffs, and the sixth to land back at Cape Canaveral. While landings have become increasingly routine, SpaceX cautioned prior to this mission that the recovery of the first stages is still somewhat experimental.

“We still will say we attempt to land,” said Hans Koenigsmann, vice president of build and flight reliability for SpaceX, at a pre-launch briefing Aug. 13. “It’s still a maneuver that is—‘audacious’ I think is the right word.”

The launch was the first for SpaceX since the July 5 Falcon 9 launch of an Intelsat communications satellite from the same pad, breaking a rapid cadence of launches SpaceX had performed prior to that. The Eastern Range, which encompasses Kennedy Space Center and Cape Canaveral Air Force Station, was down for upgrades for a month after the Intelsat launch.

At the pre-launch press briefing, NASA officials said that they had one chance to launch this mission before standing down for several days. Dan Hartman, deputy manager of the ISS program at NASA, said a planned spacewalk by two Russian cosmonauts on Aug. 17 would have coincided with a Dragon arrival at the station if launched Aug. 15. The mission would also have had to wait until the launch of a NASA communications satellite on an Atlas 5, scheduled for Aug. 18.

Heavy science payload

The Dragon is carrying 2,910 kilograms of cargo for the ISS, of which nearly 75 percent is science investigations and experiment hardware. “With the internal and external payloads that we have going up, it sets a new bar for the amount of research that we’ve been able to get on this flight,” Hartman said.

Hartman said that emphasis towards scientific investigations is enabled by the large supplies of consumables, like food and water, already on the station. “Our consumable levels are in really good shape,” he said. “When we can, we try to dedicate as much as we can to the research community.”

The science investigations on this Dragon mission are very diverse. The largest single payload is the Cosmic-Ray Energetics and Mass (CREAM) astrophysics experiment, carried in Dragon’s trunk to be mounted later on the Japanese module Kibo’s external platform. The 1,258-kilogram experiment, sometimes called ISS-CREAM to differentiate it from its balloon-borne predecessor, is designed to study cosmic rays ranging in pass from hydrogen to iron nuclei.

Other investigations carried on the mission include one funded by the Michael J. Fox Foundation to grow crystals of a protein linked to Parkinson’s Disease, an experiment to grow stem cells that could treat lung disease, and the latest in a series of rodent research experiments.

The Dragon is also carrying several satellites for later deployment from the station, including the U.S. Army’s Kestrel Eye imaging satellite and Dellingr, a six-unit cubesat developed by NASA’s Goddard Space Flight Center to perform space science experiments and perform technology demonstrations.

“Every mission we come to, it seems like the portfolio, the projects in the pipeline, are getting more and more diverse and more and more interesting,” said Ken Shields, director of operations for the Center for the Advancement of Science in Space (CASIS), the non-profit organization that manages the portion of the ISS designated as a U.S. national laboratory, at a pre-launch briefing.

The spacecraft does have some supplies for the station’s crew, and some special treats as well. Hartman said that NASA took advantage of excess capacity in the spacecraft’s freezer to include some ice cream for the station’s six-person crew.

The Dragon is scheduled to stay on the station for a little more than a month, with the exact timing driven by research needs. The Dragon will return with about 1,200 kilograms of experiments and cargo, according to Pete Hasbrook, associate program scientist for the ISS program at NASA.

The strong performance of the ISS in general, which reduced the amount of consumables on the Dragon flight, also led NASA to delay the next cargo mission to the station. On Aug. 11, Orbital ATK announced that NASA had delayed its next Cygnus mission, designated OA-8, from October to Nov. 10, citing “NASA’s revised ISS traffic planning and cargo needs” in a statement.

Hartman said that the schedule of ISS activities, including a series of spacewalks planned for late October and early November, contributed to the delay. Cargo requirments, he said, also played a role. “Actually, we were a little bit light on the OA-8 mission, so with the slip of one month we’re able to get new cargo that we need up to the station, on the order of about 400 kilograms,” he said.

The next Dragon mission to the ISS, SpX-13, is tentatively scheduled for December, Hartman said. That mission had previously been tentatively scheduled for November.